1. Field of the Invention
The invention relates to a milking installation with a milk pump.
2. Description of the Related Art
Milking installations generally include at least one set of teat cups with a plurality of teat cups through which milk flows under vacuum to a temporary storage and milk de-aeration unit e.g. a milk glass and a pump to transport the milk from the milk glass to an accumulating storage tank or to other containers. Such pumps generally are centrifugal pumps.
A drawback of the centrifugal pump is that such pumps damage the membrane surrounding the fat globules of the milk causing lypolysis and the creation of free fatty acids in the milk. This is an undesirable effect of pumping.
A solution proposed in the art and described in GB2192673 is the use of a diaphragm milk pump which reduces lypolysis occurring in the milk pumped in the milking installation. The diaphragm milk pump as described in GB2192673 includes a milk supply line through which the milk flows due to the force of gravity through a first one way valve into a first chamber. The first chamber is in open communication with a second chamber into which the milk flows under gravity and in an upper wall of the first chamber is an one way outlet valve. The second chamber is provided with a diaphragm and thus is the pumping chamber. A space between the diaphragm and the housing of the pump, isolated from the second chamber, is connected to a liquid or air pressure source that alternatingly forces the diaphragm upwards expelling fluid contained in the second chamber into the first chamber or pulling the diaphragm down allowing milk to enter the pumping chamber from the first chamber.
A drawback of the pump disclosed in GB2192673 is the fact that the pump cannot completely empty the chambers and thus a volume of milk will always remain inside the pump. Milk being an easily degradable fluid and also being susceptible to growth of spoilage organisms such as microbacteria, yeast and molds, it is highly undesirable to have a residual volume of milk present in the milk pump. The fluid remaining in the pump also prevents effective cleaning of the pump taking place. After cleaning the pump a volume of cleaning liquid would remain in the second chamber and upon resuming the milking process, milk would mix with the cleaning fluid. This contaminates milk with chemicals which again is undesirable.